Mukaiyama-Michael addition between stoichiometric amounts of a bisketene acetal and methyl vinyl ketone is rapidly followed by a double cascade intramolecular Mukaiyama-Michael addition to form a fused tricyclic compound containing four-, five- and six-membered rings embellished with several functionalities. Mukaiyama-Michael addition- cascade reaction - fused tricyclic framework -silyl enol ethers - bisketene